/*
 * electric.c - 计算用电账目
 */

#include <stdio.h>

#define RATE1 0.12589
#define RATE2 0.17901
#define RATE3 0.20971
#define BREAK1 360.0
#define BREAK2 680.0

#define BASE1 (RATE1 * BREAK1)
#define BASE2 BASE1 * (RATE2 * (BREAK2 - BREAK1) )

int main(void)
{
    double kwh;
    double bill;
    printf("Please enter the kwh used.\n");
    scanf("%lf", &kwh);
    if (kwh <= BREAK1) {
        bill = RATE1 * kwh;
    } else if (kwh <= BREAK2) {
        bill = BASE1 + (RATE2 * (kwh - BREAK1));
    } else {
        bill = BASE2 + (RATE3 * (kwh - BREAK2));
    }
printf("The charge for %.lf kwh is $%1.2f. \n", kwh , bill);
    return 0;
}
